1. Field of the Invention
The present invention relates to a motor driving control apparatus for controlling the driving of a motor used in a machine tool, a forging press, an industrial machine, etc.
2. Description of the Related Art
In the prior art, for example, in JP3252114B, JP2004-166477A, JP2008-225652A, and JP2008-43057A, a motor driving control apparatus that controls the output of a motor (for example, a servo motor) by determining a command value to be supplied to a motor driving unit to drive the motor, wherein a control parameter for controlling the motor is set based on the voltage of an AC power supply (for example, a three-phase AC power supply) that supplies power to the motor, and the command value is determined based on the control parameter is proposed.
According to such a motor driving control apparatus, since the control parameter can be set by responding to changes in the voltage of the AC power supply, the output of the motor can be controlled appropriately according to the changing voltage of the AC power supply.
The amount of voltage drop that an AC power supply may experience varies depending on the environment where the AC power supply is installed. For example, the amount of voltage drop that occurs when a single AC power supply is supplying power to a plurality of motors is larger than the amount of voltage drop that occurs when a single AC power supply is supplying power to a single motor. When a single AC power supply is supplying power to a plurality of motors, if any of the motors accelerates or the motor speed reaches a maximum speed, the motor output increases and the voltage of the AC power supply further drops, increasing the possibility of adversely affecting the driving of the motors and eventually causing the motors to stall.
However, with the prior art motor driving control apparatus, when the voltage of the AC power supply drops to a level that adversely affects the driving of the motor, since the motor only delivers an output corresponding to the voltage level that adversely affects the driving of the motor, it is not possible to avoid a drop in the voltage of the AC power supply which adversely affects the driving of the motor.
It is an object of the present invention to provide a motor driving control apparatus wherein provisions are made to prevent the driving of a motor from being adversely affected by a voltage drop that may occur with an AC power supply that supplies power to the motor.